I am lazy. I select my mesh, U -> Smart Unwrap -> Ok. And I would go on and texture it with SubstancePainter or Photoshop. I only create low Poly stuff and this has worked perfectly sofar. Everything is in correct angle and proportion:
More and more often I get resulst like these, even though I have "Correct Aspect" checked. This makes it impossible to work with:
Tweaking values doesn't fix anything. The Unwrapped Mesh is in inappropriate proportions and it stays this way. It's actually FASTER to redo the entire model and unwrap it again than to complicately mark seams and fiddle with the Mesh in the UV-Editor. Unless of course it comes out bugged again, but sofar that was never the case. The model is pretty much equal, the result is totally out of whack.
What is happening here behind the curtains that I don't see/understand?